Stoker fired boiler installation



May 26, 1931. E. LUNDGREN STOKER FIRED BOILER INSTALLATION Filed Aug. 5. 1927 35 Snom/Joa:

@HQI/14W A im rove stoker fired boiler installations.

Patented May 26, 1931 UNITED lSTATES PATENT OFFICE EDWIN LUNDGREN, OF FREDERICK, MARYLAND, ASSIGNOR T0 INTERNATIONAL GOM- ZBUSTION ENGINEERING CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE STOKER FIRED BOILER INSTALLATION This invention relates to means for improving stoker fired boiler installatlons.

One 'of the objects of my inventlon 1s to propose to line the walls of the combustion chamber with evaporatinsurfaces, such as water tubes, whereby in a oiler installation of relatively small size, relatively high capacities may be developed. In stoker fired installations, however, full advantage cannot be taken of such an arrangement for the reason that the grate area cannot be made large enough to carry peak load capacities. I propose to operate the stoker at its most economical rate and to develop the potential capacity, by supplementing the stoker liring by means of inely dividedfuel firing at times of peak load.

A more specific object is to equip a Stoker fired installation of the above character w1th improved means whereby it may be slmply and effectively supplemented by nely d1- vi'ded fuel firing.

A further object of my invention 1s to eeca tively subject the convection tubes of the boiler to the iow of the gases.

Still another object'of my inventlon has to do with an arrangement of parts whereby `the finely divided fuel burner is protected against burning out when firing by means o the stoker alone.

How the foregoing, together with such other objects land advantages as may herein-` after appear, orare incident to my invention are realized is illustrated in preferred form in the accompanying drawings wherein- Figure 1 is a sectional elevation through a boiler installation constructedin accordance with my invention; and

Figure 2 is affragmentary. transverse section taken just in front of the tubes of the rear wall and looking toward the burner means. A

The installation comprises in general a combustion chamber A having a stoker B for the burning of solid fuel thereon; a tubular boiler C located above the combustion chamber; an extension chamber D located at the rear of the combustion chamber; and burner :lfnueans E for the burning of finely divided e The combustion chamber A is largely defined by tubular water walls, the side walls (one of which only appears inthe drawings) belng formed of two groups of upright tubes 2 and 3, preferably finned, the front wall by l the finned tubes 4 and the refractory portion 5 and the rear wall in part by the tubes 6.

The tubes of the group of tubes 2 are connected at their lower ends into a header 7 and at their upper ends into a header 8, and the tubes of the group of tubes 3 are connected at their lower ends into a header 9 and at their/upper ends' into the header 8. The tubes 4 are connectedat their lower ends into a header 10 and at their upper lends into a header 11. The lower headers 7, 9 and 10 are connected to the drum 12 of the boiler C by means of downcomers 13 and the upper headers are connected to the boiler by means of upcomersl 14 and 15. Downcomers 16 l'from the drum 12 connect the tubes 6 of the rear wall with 4said drum through the Inedium of the lower header 17 and the upper ends of these tubes are connected into a headj are subject to radiant heat from the llame of j the Stoker and that the gases'of combustion pass upwardly and over the convection tubes of the tubular boiler C, the boiler being a onepass boiler.

. Above the convection tubes of the boiler I have located a plurality of baffles 19 for the purpose of causing the gases to cover the entire area of the boiler tubes so as to effectively subject them to the action of the gases. The gases after leaving the channels provided, by the bailies pass into the flue 2O which is connected with the stack and in which suitable draft mechanism may be located. This. is an arrangement .which secures more uniform distribution ofl'low cross-sectionally of the radiant heat tubes, the sunerheater, and the convection tubes of the boiler.

By the provision of a combustion chamber of the character above described, it will be seen that the installation is one in which very high capacities may be developed relative to its size but inasmuch as the space available for grate surface is limited, the grate area is insufficient to enable the development of the potential capacity of the installation with economical operating of the stoker. To develop the potential capacity I propose to operate the Stoker at its most economical rate and to supplement it by bringing into action the pulverized fuel burner means E now to be fully described.

At the rear of the combustion chamber A I provide the extension or mixing chamber D into which pulverized fuel is introduced by means of a burner or.burners E, in this instance illustrated as one adapted to inject the fuel in such manner as to cause the fuel and fiame Stream to pass radially and outwardly into the combustion chamber. The burner is preferably upwardly tilted so as to direct the flame away from the Stoker fuel bed. Air, in addition to carrying air, is introduced around the burner by means of a plurality of air ports 21, which air is preferably preheated as by means of an air preheater 22 located in the flue 20. This air is led from the preheater to the air chamber 23 surrounding the burner by means of a conduit 24 in which a fan 25 is located. A damper 23a is provided to control this air.

Secondary air is introduced into the mixin chamber D from the air chambers 26 and 27, which chambers are defined in part by spaced inclined water tubes 28 and 29. The tubes 28 are connected at their lower ends into theheader 17 hereinbefore mentioned, and at their upper ends into a header 30, and the tubes 29 are connected at their lower ends into a header 31 and at their upper ends into the header 18 hereinbefore mentioned. The headers 30 and 31 are connected by means of tubes 32. Thus, it will be seen that there is an upward circulation in the tubes 28 and 29. It is to be noted that the lower portion of the tubesC 28 and the upper portion of the tubes 29 are finned, and that these tubes ars so disposed that these portions are interspersed with the rear wall tubes 6. l

Air is led to the chambers 26 and 27 by means of a duct 33 having openings 34 communicating with the chambers and a damper controlled opening 35 communicating with the conduit 24. Air from these chambers ent-ers the mixing chamber D through the spaces between the tubes 28 and 29. Thus, intimate mixture of fuel and air is ensured.

From the foregoing it will be seen that I have provided an improved Stoker fired in- Stallation in which very high capacities can be developed while always maintaining most economical and efhcient operation of the Stoker. Y

The space afforded by the extension chamber D is more or less dead space when firing with the Stoker alone, although there will be considerable transmission of heatfby radiation, in consequence of which the extension Vchamber is always effective. When suppleinenting the Stoker with pulverized coal, this additional space is utilized for mixing and ignition andthus constitutes an addition to the combustion space, making it possible to effectively supplement the stoker.

The arrangement of the chamber D with its water tubes 28 and 29 is one which affords protection of the burner means E against burning out when it is not in operation, that is to say, when the installation is being fired by the Stoker alone.

Obviously, the pulverized fuel supplying equipment can be relatively small, as such fuel is only required at times of peak load. The invention may be applied to existing installations and ratings may then be secured far above those otherwise possible.

I claim 1. A boiler installation including a Stoker fired combustion chamber having an exten- Sion chamber, spaced water tubes in said eX- tension chamber so located as to provide air chambers in said extension chamber, means for admitting air to said air chambers, and burner means located in Said extension chamber for introducing finely divided fuel to be burned in space, the air from Said air chambers passing through the spaces between said water tubes for admixture with the nely divided fuel.

2. In combination, a boiler installation including a combustion chamber', thecombustion space of which is largely defined by steam evaporating tubes subject to radiant heat, a tubular boiler associated with said chamber, a Stoker for burning lump fuel in said chamber, the steaming capacityv of the installation being greater than can be developed by the Stoker with economical operation thereof, and means for supplementing the Stoker firing by finely divided fuel firing to develop the potential capacity of the installation, said means including an extension chamber communicating with the combustion space for securing ignition of the nely divided fuel, burner means for introducing said fuel into the chamber, and protective means for the burner.

3. In combination, a boiler installation including a combustion chamber, the combustion space of which is largely defined by steam evaporating tubes Subject to radiant heat, Ya tubular boiler associated with said chamber, a Stoker for burning lump fuel in said chamber, the steaming capacity of the installation being greater than can be developed by the Stoker with economical operation thereof, and means for supplementing the Stoker firing by finely divided fuel firing to develop the potential capacity of the installation, said means including a chamber built out from a side wall of the installation and communicating with the combustion space for securing ignition of the finely divided fuel, burner means for introducing said fuel into thechamber, and means in said chamber for protecting said burner means.

4. A boiler installation including a Stoker fired combustion chamber, an extension chamber formed in a wall of said lcombustion chamber, water tubes lining said Wall, certain of which extend into the extension chamber, and burner means located in said extension chamber 'for the introduction Hogf linely divided fuel and air. E

5. A boiler installation including a Stoker ired combustion chamber, a wall of said chamber having an opening, an open end casing fitting said opening to provide an extension chamber inthe wall opening into. the combustion chamber, burner means located in said extension chamber for the introduction of finely divided fuel and air, and steam evaporating surfaces in said extension chamber arranged to protect the burner from high heat during stoker opertion of the installatlon.

In testimony whereof I have hereunto signed my name.

EDWIN LUNDGREN. 

